Enhanced performance of mineral based aqueous barrier coatings

ABSTRACT

A method for preparing an aqueous based coating system, and coating systems made thereby, for coating onto paper and/or paperboard for providing barrier to liquid, moisture vapor, oil and grease including a pigment and a polymer emulsion system or natural based binding system. One alternative of the method includes surface treating a pigment to form a pigment system and mixing a polymer emulsion system or natural based binding system with the pigment system. Another alternative of the method includes mixing a pigment and polymer emulsion system or natural based binding system and hydrophobizing the polymer emulsion system or natural based binding system by adding silanes, siloxanes, siloxane/silicone resin blends, or their carbon based analogs.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 12/861,626 filed Aug. 23, 2010, which claims benefit to U.S.provisional application No. 61/236,286 filed on Aug. 24, 2009, theentire contents of both are incorporated by reference herein.

FIELD OF THE INVENTION

The disclosure is directed to high performance pigment containingcoating systems for use in aqueous-based barrier coatings. Inparticular, the disclosure includes novel pigment systems and blendingtechnologies applied to aqueous based coating systems that will providedesired properties in paper and paper board based packaging.

BACKGROUND

Corrugated fiberboard containers are used in many high humidity bulkpackaging applications such as for fresh fruit and produce items. Toovercome the known impairment in the strength of corrugated fiberboardin high humidity service, it is customary to treat such containers, orthe corrugated fiberboard sheets or blanks from which the containers areformed, by impregnating them with a material resistant to moisture.

Applications can also include films for food items such as cookie andcracker packaging. In these particular cases, the object of the packageis not only to hold the contents, but also to provide resistance tomoisture vapor transmission (from the environment to inside thepackage). Otherwise, moisture vapor would diminish the shelf life of thecontained cookies, crackers, or the like. Shelf life is determined bythe time it takes the products to pick up sufficient moisture to renderthem stale. In cookie and cracker packaging applications, for example,the general object of the barrier layer is to substantially keepmoisture out or to slow its ingress.

In the past, external coating layers of high density polyethylenes(HDPE) were needed to achieve a target water vapor transmissionresistance (WVTR) or aqueous fluid (hot or cold) transmissionresistance. Typically, these external coatings also included theaddition of a second coating layer to provide other desired propertiessuch as tear resistance, and/or mechanical properties such as heat seal.Often the materials used in the second coating layer were relativelypoor in WVTR or aqueous fluid (hot or cold) transmission resistance.

Such combinations typically result in added costs and may affect otherimportant properties necessary to the packaging industry. Therefore, aneed exists for a moisture barrier film or container fabricated suchthat the article will have relatively good WVTR or aqueous fluid (hot orcold) transmission resistance combined with improved physicalproperties.

SUMMARY

This disclosure is directed to novel pigment systems (includingcomponents not classified as pigments) and formulations for use in anaqueous coating system applied onto cellulosic (paper and/or paperboard)and non-cellulosic substrates (polyethylene (PE), polylactic acid (PLA),polyvinyl acetate (PVAc), etc.) to impart barrier properties. Thisdisclosure is also directed to a paper or paperboard coated with apigment system in an aqueous coating system.

In a first aspect, the disclosure relates to a method for preparing anaqueous based coating system for coating onto paper and/or paperboardfor providing barrier to liquid, moisture vapor, oil and grease. Themethod includes the steps of surface treating a pigment to form apigment system, and mixing a polymer emulsion system or natural basedbinding system with the pigment system.

In a second aspect, the disclosure relates to an aqueous based coatingsystem for coating onto paper and/or paperboard for providing barrier toliquid, moisture vapor, oil and grease. The coating system includes apolymer emulsion system or natural-based binding system and a pigmentsystem. The pigment system comprises a surface treated pigment.

In a third aspect, the disclosure relates to a coating system forcoating onto a paper and/or paperboard. The coating system includes apigment and a polymer emulsion or natural-based binding system that hasbeen hydrophobized by the addition of materials selected from the groupconsisting of silanes, siloxanes, siloxane/silicone resin blends, andtheir carbon-based analogs.

In a fourth aspect, the disclosure relates to a method for preparing anaqueous based coating system for coating onto paper and/or paperboardfor providing a barrier to liquid, moisture vapor, oil and grease. Themethod includes the steps of mixing a polymer emulsion system or naturalbased binding system with a pigment, and hydrophobizing the polymeremulsion system or natural based binding system by adding a materialselected from the group consisting of silanes, siloxanes,siloxane/silicone resin blends, and their carbon-based analogs.

In an embodiment of any of the four aspects, the pigment or pigmentsystem is modified by a thermal treatment process.

In an embodiment of any of the four aspects, the pigment is surfacetreated with materials selected form the group consisting ofsurfactants, hydrophobically-modified polymers, styrene-acrylic resinemulsion, styrene-butadiene latex emulsions, blends of styrene acrylicand styrene butadiene latex emulsions, and silanes, siloxanes,siloxane/silicone resin blends, and their carbon-based analogs.

In an embodiment of any of the four aspects, the pigment is at least oneinorganic material selected from kaolin, bentonite, mica, talc,attapulgite, and zeolite.

In an embodiment of any of the four aspects, the polymer emulsion systemcomprises a styrene-acrylic resin emulsion.

In an embodiment of any of the four aspects, an additive to improveblocking is added to the polymer emulsion system or natural basedbinding system and pigment system.

In a certain embodiment of any of the four aspects, the additive toimprove blocking comprises a material selected from the group consistingof calcium stearate, styrene-acrylic resin, acrylic resin, andpolyethylene-paraffin wax emulsion.

In a certain embodiment of any of the four aspects, the pigment systemcomprises surface treated kaolin having a particle size of at least 20%by weight finer than 2 micrometers.

As used herein, the term pigment refers to minerals as known to oneskilled in the arts as, for example, kaolin, bentonite, mica, talc,attapulgite and zeolite, in their natural or synthetic form and anycombination thereof. Pigment systems refer to pigments that have beensurface treated to enable or improve barrier properties. The surfacetreatment comprises treating with various materials known to one′skilled in the art, for example, surfactants, hydrophobically-modifiedpolymers, styrene-acrylic resin emulsion, styrene-butadiene latexemulsions, blends of styrene acrylic and styrene butadiene latexemulsions, and silanes, siloxanes, siloxane/silicone resin blends, andtheir carbon-based analogs.

As used herein, the term polymer emulsion or latex includes materialssuch as acrylic resin emulsions, styrene-acrylic resin emulsions,styrene-butadiene latex emulsions, and blends of styrene acrylic andstyrene butadiene latex emulsions. Monomers suitable for use in theproduction of emulsion systems for paper coating or binding formulationcan generally be ethylenically unsaturated monomers including styrene,butadiene, vinyl acetate, carboxylic acids, (meth)acrylic acid esters,(meth)acrylamide, and (meth)acrylonitrile. As used herein, the termnatural-based binding system is known to one skilled in the art as, forexample, starches, proteins and caseins.

Polymer emulsion system refers to polymer emulsions and variousadditives, such as a cross linker or a defoamer, that when combined withthe pigment or pigment system make the coating system.

As used herein, the term emulsion system refers to various emulsions forcombining with the pigment system to develop the coating system.Emulsion systems (also commonly referred to as latexes) comprisestyrene-acrylic resin emulsion, styrene-butadiene latex emulsions,blends of styrene acrylic and styrene butadiene latex emulsions etc.Monomers suitable for use in the production of emulsion systems forpaper coating or binding formulation can generally be ethylenicallyunsaturated monomers including styrene, butadiene, vinyl acetate,carboxylic acids, (meth)acrylic acid esters, (meth)acrylamide, and(meth)acrylonitrile.

As used herein, the term “inorganic materials” includes materials suchas carbides, oxides and nitrides.

DESCRIPTION OF PREFERRED EMBODIMENTS

This disclosure is related to a pigment and a coating system design thatsignificantly slow the transportation kinetics of target species such asliquid, moisture vapor, oil and grease. It involves manipulation of thephysical attributes of elements of the aqueous coating system;specifically the pigment system being used and/or the binder systembeing employed.

In certain embodiments, the physical attributes of the pigment includeat least one of the following:

-   -   The pigments having acceptable morphology appropriate to a given        application;    -   Controlled surface area, engineered morphology particles;    -   Ultrafine size particles;    -   Highly porous particles having pore size distribution and        surface area tailored to the target barrier coating application;        and    -   High surface area particles.

The pigment may also undergo a thermal treatment process and then, withor without the thermal treatment, can be subjected to a surfacetreatment that will facilitate repulsion of water and/or significantlyslow the rate of diffusion of the target species (high surface tensionor contact angle). Surface treatments may include but are not limitedto:

-   -   Surfactants such as stearates;    -   Hydrophobically modified polymers such as polyethylenimine        (PEI);    -   Styrene-acrylic resin emulsion chemistries;    -   Styrene-butadiene latex chemistries;    -   Synergistic blends of styrene acrylic and styrene butadiene        latex chemistries; and    -   Surface treatments including but not limited to silanes,        siloxanes, siloxane/silicon resin blends, and their carbon-based        analogs.

The pigment system can be a stable slurry that can contain any of thecombination of pigments described above as well as a dispersant, anoptional defoamer and a thickener. The dispersant can be a latex, starchor polyvinyl alcohol (PVAL). Natural thickening aids such as starch orprotein or synthetic polymers such as Sterocoll FS (available from BASFCorporation) can be used to thicken and/or stabilize the pigment system.

In certain embodiments, the pigment system is mixed with a polymeremulsion system, a natural based binding system, or a combinationthereof. Surface treated pigments cannot be made down in water, becausesuch surface treated pigments float in water. The inability to be madedown can result in poor rheological stability, fisheyes, and/or coatingunevenness. However, the addition of a polymer emulsion system or anatural based binding system to the water can remedy many of theseproblems. The polymer emulsion system or natural based binding systemcan be added to the aqueous based coating system in an amount of 5 to 75parts. In particular embodiments, the polymer emulsion system or naturalbased binding system is added in amounts of 5 to 50 parts, 5 to 35parts, 10 to 20 parts, or about 10 parts. In more particularembodiments, the polymer emulsion system is a styrene-acrylic emulsion.In certain embodiments, the polymer emulsion system can be a soft filmforming styrene-acrylic emulsion that provides flexibility and waterresistance, and is allowed to be used in direct food contactapplications. In particular embodiments, the styrene-acrylic emulsioncan have an acid number (NV) of from 50-75, 55-70, or 60-65. In certainembodiments, the styrene-acrylic emulsion can have a glass transitiontemperature (Tg) measured in degrees Celsius of from −50 to 0, −40 to10, −30 to 20, or −30 to 25. An exemplary styrene-acrylic emulsion foruse as the polymer emulsion system is Joncryl 3030, which is astyrene-acrylic resin emulsion from BASF Corporation.

The barrier coating formulation can comprise or consist of the pigmentsystem, an optional defoamer/deaeration/antifoam agent, a cross linker(glyoxal or AZC for example), and a binder. The binder can be a styreneacrylic resin emulsion (SA), a styrene butadiene latex (SB latex),acrylic resin emulsion, PVAL, starch, protein and a combination thereof.The binder can also contribute to the barrier properties.

The barrier coating formulation can also comprise additives to improvethe blocking tendency of the coated paperboard. Additives that improveblocking include calcium stearate, styrene-acrylic emulsions, acrylicemulsions, polyethylene-paraffin wax emulsions, and minerals such astalc or mica. Blocking tendency of the coated paperboard can also beimproved by using particular pigment-resin ratios. In certainembodiments, the pigment to resin ratio is from 10:1 to 1:10, from 5:1to 1:5, from 4:1 to 1:4, from 3:1 to 1:3, from 2:1 to 1:2, from 1.5:1 to1:1.5, or about 1:1.

To further illustrate embodiments of the invention, various examples aregiven below. Throughout these examples, as well as the rest of thespecification and claims, a variety of coating systems were made andevaluated. These systems contain both latexes and pigment systems(unless otherwise specified). The water resistance of the coatings wasmeasured using the Cobb method described by TAPPI method T 441.

Example 1—Styrene Acrylic Resin Emulsion/Kaolin Coatings

Eight kaolin-based pigment systems were developed and tested in acoating system comprised of 50 parts (dry basis) (styrene acrylic latexemulsion (SA), 50 parts pigment system (dry basis) and 0.001% defoamer.The SA utilized in this testing phase was a blend of commerciallyavailable styrene acrylic resin emulsions produced by BASF Corporation.It is characterized by a solids content of 46% by weight, a pH of 8.3,an acid number of 75 and a Tg(C) of 19. It was designed to give goodwater and grease resistance to food packaging

The SA emulsion and defoamer (Octafoam DFI-51 by Hi Mar SpecialtyChemicals) were weighed into a small stainless steel beaker and mixedwith a Dispermat mixer fitted with a saw toothed blade. Mixing speed wasramped up until a vortex was created at the agitator shaft. The pigmentsystem was added gradually into the liquid vortex. Once addition wascomplete, the mixer speed was increased to 1200 rpm and the coatingsystem was allowed to disperse for 10 minutes. The total sample size wasapproximately 100 g. Coating system solids were targeted at 59.0percent.

An embodiment of the pigments/pigment systems used in this study isdescribed in Table 1 (below). Two commercially available kaolin pigmentswere used in the study. The kaolin pigment is platy, having a particlesize of 50% by weight finer than 2 micrometers, which is referred toherein as coarse kaolin. The product was initially dried in aflocculated state (3.2 pH) and then dispersed in water with sodiumhydroxide to a 7.0 pH. This slurry was then subjected to surfacetreatment. The fine kaolin pigment is platy, having a particle size of90% by weight finer than 2 micrometers and an intermediate aspect ratio.The product was initially dried in a flocculated state (3.2 pH). The lowpH dry fine kaolin was surface treated with 1.0 percent magnesiumstearate for one experiment and also dispersed in water with sodiumhydroxide to a 7.0 pH. This slurry was then subjected to surfacetreatment.

Surface treatments included in the study:

-   -   Treatment A: A blend of commercially available SA emulsions        (available from BASF Corporation) was used. The composite was        formulated for special grease resistance for surface sizing        using a process known to the skilled artisan. The resulting        product has a pH of 7.3, Acid Number of 108 and a Tg(C) of 14.0.        1.0 weight percent of the SA emulsion was added to the kaolin.    -   Treatment B: A small particle size, very low volatile organic        compound (VOC) polyethylene/paraffin wax emulsion (BASF        Corporation) designed for water shedding, heat release and low        COF with FDA acceptability was used. The product pH was 9.0,        Acid Number of 56, and a Tg(C) of 0.08. 1.0 weight percent of        the polyethylene/paraffin wax emulsion was added to the kaolin.    -   Treatment C: A general purpose, soft film forming SA emulsion        (BASF Corporation) for use in water based flexo and gravure inks        on flexible films and foil. The product pH was 8.3, Acid Number        of 50, and A Tg(C) of −30. 1.0 weight percent of the SA emulsion        was added to the kaolin.    -   Treatment D: A soft film forming acrylic emulsion (available        from BASF Corporation) that provides film formation, excellent        rub resistance, and water and grease resistance was used. The        product pH was 8.3, Acid Number of 50, and a Tg(C) of −16. 1.0        weight percent of the acrylic emulsion was added to the kaolin.    -   Treatment E: An experimental hydrophobized polyethylenimine        (PEI) (MW=800 g/mol) modified with 20% addition of lauric acid        (MW=1550 g/mol) was used. 0.5 weight percent of the PEI (dry on        dry basis) was added to the kaolin.    -   Treatment E: An experimental hydrophobized polyethylenimine        (PEI) (MW=5000 g/mol) modified with 20% addition of stearic acid        (MW=9660 g/mol) was used. 0.5 weight percent of the PEI (dry on        dry basis) was added to the kaolin.    -   Treatment G: Magnesium stearate. 3.0 weight percent added to the        kaolin.

TABLE 1 A Fine kaolin/Treatment G B Coarse kaolin/Treatment A C Coarsekaolin/Treatment B D Coarse kaolin/Treatment C E Coarse kaolin/TreatmentD F Coarse kaolin/Treatment E G Coarse Kaolin/Treatment F H FineKaolin/Treatment E

The coatings were applied to a Kraft paper, with characteristicsdescribed in Table 2.

TABLE 2 Characteristics of Kraft Paper Basis weight (g/m²) 100 Roughness(mm) 7.3 Bendtsen permeance (ml/min) 4464

The Kraft paper selected had a relatively high permeance. As such, aprime coat of a blend of commercially available SA emulsions was appliedto each kraft sheet to be coated. The blended product pH was 8.3; AcidNumber was 75 and had a Tg(C) of 19.0. This first layer was applied witha #2 Meyer Rod (wire wound bar) on a K-Coater and dried for 1 minute at50° C. The resultant coating weights were 3.0 g/m² of dry coating.

Each experimental coating system was applied to the pre-coated kraftbase sheet with a #3 Meyer Rod and dried 1 minute at 50° C. targeting acoating weight of 13.0 g/m² dry coating. The test sheets were thenallowed to equilibrate in a constant temperature and humidityenvironment at 25.5° C. and 40% R.H. before testing.

The control for this series of tests was prepared by coating the samekraft paper twice with SA emulsion blend used to precoat the kraft basepaper. This yielded the same total dry coat weight as applied toexperimental samples containing 50 weight percent pigment in coatingsystems.

Water barrier properties were assessed by running the Cobb testaccording to TAPPI method T 441, with a test area of 100 cm² and a testtime of 2 minutes. To summarize, a 100 cm² is cut from the coated sheetand weighed to 0.0001 g. The sample was then placed into a test jigcoated side up and a metal ring clamped over it. 100 mL of water waspoured into the ring and allowed to sit for 2 minutes. At that time, thewater was poured out, the sample unclamped and surface dried off withblotting paper and a controlled weight, and the sample reweighed. The“Cobb value” is a measure of how much water the sample has absorbed andis calculated by the equation:

${Cobb} = \frac{{mass}_{aftersoak} - {mass}_{initial}}{area}$

Results are reported in units of g/m². Lower Cobb values indicategreater water resistance.

In this round of testing, three samples of each coating system weremeasured. The results of the Cobb tests are summarized below in Table 3.

TABLE 3 Water resistance - 2 minute Cobb ID Sample Composition 2 minCobb (g/m²) A Fine kaolin/Treatment G 36.8 B Coarse kaolin/Treatment A4.3 C Coarse kaolin/Treatment B 13.1 D Coarse kaolin/Treatment C 5.9 ECoarse kaolin/Treatment D 19.2 F Coarse kaolin/Treatment E 13.9 G Coarsekaolin/Treatment F 6.2 H Fine kaolin/Treatment E 44.4 Control Pre-coatSA emulsion blend 66.0

Coating systems B, C, D, F, and G offered the most significantimprovement in Cobb and were statistically better than the control. Allof the pigments in the pigment systems of the above examples areconsidered coarse and platy. Synergies were also seen when a styreneacrylic resin emulsion was used for surface treatment. The surfacetreatment process was of significant importance. Here, the kaolinpigment was first mixed with SA emulsion forming a slurry (15 to 60percent solids). The slurry was then dried to both encapsulate andanchor the treatment onto the surface of the pigment. This allowed theunique physical properties of a pigment system to take on chemicalcharacteristics of the SA resin coating.

A second unexpected finding was the ease in which hydrophobicallytreated kaolin pigments can be dispersed into a styrene acrylic resinemulsions. No extensive work input (shear) or temperature manipulationwas required to effect formation of a stable slurry. There was noevidence of a chemical interaction during the mixing process as well. Insummary, correctly formulated coatings can be pigmented to give improvedwater resistance.

There are a range of styrene acrylic resin (SA) emulsions available inthe marketplace. The performance factors engineered into the emulsionTg(C), acid number, viscosity, etc.) can greatly influence the barrierperformance factors of a given coated substrate. To further demonstratethe viability of the findings in Example 1, the study was repeated withcoating prepared using Epotal S 440 styrene acrylic resin emulsion fromBASF Corporation. Epotal S 440 is a soft film forming emulsionengineered for direct contact with food. The product pH is 8.0, AcidNumber of 64, and a Tg(C) of −27.

Example 2—Coatings with Treated Kaolin Pigment System and Epotal S 440

Eleven kaolin-based coating samples were prepared and analyzed duringthis study. Surface treatments for this study included:

-   -   Treatment A: A blend of commercially available SA emulsions from        BASF Corporation was used. The product had a pH of 7.3, Acid        Number of 108 and a Tg(C) of 14.0. 1.0 weight percent of this        product was added to kaolin.    -   Treatment B: A commercially available (BASF Corporation) small        particle size, very low VOC polyethylene/paraffin wax emulsion        designed for water shedding, heat release and low COF with FDA        acceptability. The product pH was 9.0, Acid Number of 56, and a        Tg(C) of 0.08. 1.0 weight percent of this product was added to        kaolin.    -   Treatment C: A commercially available (BASF Corporation),        general purpose, soft film forming SA emulsion for use in water        based flexo and gravure inks on flexible films and foil was        used. The product pH was 8.3, Acid Number of 50, and A Tg(C) of        −30. 1.0 weight percent of this product added to kaolin.    -   Treatment D: A commercially available, soft film forming acrylic        emulsion (BASF Corporation) that provides film formation,        excellent rub resistance, and water and grease resistance was        used. The product pH was 8.3, Acid Number of 50, and a Tg(C) of        −16. 1.0 weight percent of this product was added to kaolin.    -   Treatment E: An experimental hydrophobized polyethylenimine        (PEI) (MW=800 g/mol) modified with 20% addition of lauric acid        (MW=1550 g/mol) was used. 0.5 weight percent of the PEI (dry on        dry basis) was added to the kaolin.    -   Treatment E: An experimental hydrophobized polyethylenimine        (PEI) (MW=5000 g/mol) modified with 20% addition of stearic acid        (MW=9660 g/mol) was used. 0.5 weight percent of the PEI (dry on        dry basis) was added to the kaolin.    -   Treatment G: Magnesium stearate. 3.0 weight percent of this        product was added to kaolin.    -   Treatment H. Commercially available siloxane hydrophobizing        substituents (from Momentive Performance Materials). 2.0 weight        percent of this product was added to kaolin.

The coarse, platy hydrous kaolin pigment described in Example 1 was usedin nine of the pigment systems for this study. Sample B, Translink 37,is a commercially available calcined kaolin that has been surfacetreated with siloxane based hydrophobizing chemistry. This BASF pigmentdoes not have a platy or coarse morphology. In Sample P, the dispersionchemistry of the coarse, platy hydrous kaolin pigment was modified toinclude a sodium polyacrylate (molecular weight in the 3500 range).

The coatings tested in this report were comprised of 50% pigment system(dry basis), 50% Epotal S 440 (on a wet basis), and 0.1 parts OctafoamDFI-51 defoamer by Hi Mar Specialty Chemicals. Target coating solidswere 59.0%. Epotal S 440 has a solids content of 49.4 wt %, so the totalweight of the emulsion was 20.24 parts.

Epotal S 440 and the defoamer were weighed into a small stainless steelbeaker and mixed with a Dispermat mixer fitted with a toothed blade at arelatively low speed to start. The pigment system was added graduallyinto the vortex, and once the full amount had been added, the mixingspeed was increased to 1200 rpm and mixing proceeded for 10 minutes. Itwas also necessary to add some water to these samples to maintain aworkable viscosity of 1000 cps. The total sample size was approximately100 g. The pigments used in this study are described below:

TABLE 4 A Fine kaolin/Treatment G B Translink 37 C Coarse kaolinuntreated D Coarse kaolin/Treatment H E Coarse kaolin/Treatment G FCoarse kaolin/Treatment A G Coarse Kaolin/Treatment B H Coarsekaolin/Treatment C I Coarse kaolin/Treatment E J Coarse kaolin/TreatmentF K Sodium polyacrylate dispersed coarse kaolin untreated

With the exception of C and K, all kaolin pigments were surface treated.All pigment samples in the above examples readily dispersed anddemonstrated good shelf stability. A few displayed some syneresis withsoftly settled pigment that was easily stirred back in. The coating madewith pigment system D, however, had a layer of firmly settled pigment atthe bottom which required some energy to stir and shake back into theliquid phase—a characteristic of well dispersed samples.

The coatings were tested on kraft paper, with characteristics describedin Table 5:

TABLE 5 Basis weight (g/m²) 100 Roughness (mm) 7.3 Bendtsen permeance(mL/min) 4464

Because the paper had a relatively high permeance, a prime coat ofEpotal S440 was first diluted to 31% solids and applied to every sheetbefore the experimental coating. This first layer was applied with a #2Meyer Rod on the K-Coater, and dried for 1 minute at 50° C., yielding adry coating weight of 3.0 g/m². Each experimental coating was thenapplied with a #3 Meyer Rod and dried 1 minute at 50° C., yielding a drycoating weight of 13.0 g/m². The test sheets were allowed to equilibratein a constant temperature and humidity environment at 25.5° C. and 40%R.H. before testing.

The control for the pigmented coatings was generated using 100%undiluted Epotal S 440, which conveniently had the same solids contentas the pigmented coatings. The control kraft sheets were first primecoated with diluted Epotal S 440 and then coated (one coat) of theundiluted emulsion equivalent to 13.0 gm² of dry coating.

The results of the Cobb tests are summarized below in Table 6.

TABLE 6 Water Resistance vs. Pigment System ID Sample Composition 2 minCobb g/m² A Fine kaolin/Treatment G 3.4 B Translink 37 1.4 C Coarsekaolin Untreated 7.5 D Coarse kaolin/Treatment H 3.0 E Coarsekaolin/Treatment G 3.3 F Coarse kaolin/Treatment A 2.1 G Coarsekaolin/Treatment B 2.4 H Coarse kaolin/Treatment C 2.1 I Coarsekaolin/Treatment E 1.5 J Coarse kaolin/Treatment F 1.0 K SodiumPolyacrylate dispersed 6.3 coarse kaolin untreated L Control - 100%Epotal S 440 3.9

All of the coating systems containing surface treated pigment systemsoutperformed the control. The performance of Pigment B, Translink 37,points to a finding that, once surface treated, calcined kaolin can beeffectively utilized in water barrier applications. This is asignificant finding in the development of water barrier coating systems.

The benefit of using the styrene acrylic resin emulsion used as asurface treatment was confirmed in this study. The Cobb values of thetwo coating systems containing untreated coarse and platy morphology(Coatings C and K) were poorer than Epotal S 440 control (Coating L).The Cobb values on the same kaolin pigment when surface treated withstyrene acrylic resin emulsion (Coatings F, G, and H) were all betterthan the Epotal S 440 control coating.

When comparing the results from Examples 1 and 2, the impacts of thepigment systems are similar. When comparing styrene acrylic resinemulsions, the Epotal S 440 makes much more water resistant coatings.This could be due to the lower Tg(C) of Epotal S 440 (−27° C. vs. 19°C.), as softer polymers tend to form more continuous films when dried.

Example 3—Hydrophobizing Styrene Acrylic Resin Emulsions

Examples 1 and 2 demonstrated the ease in which hydrophobically surfacetreated pigments could be dispersed in styrene acrylic resin emulsion. Anumber of studies were subsequently conducted to determine whether thisfinding could be extended to develop a method for hydrophobizing astyrene acrylic resin emulsion in lieu of surface treating the pigmentcomponent of the barrier coating system. Silane, siloxane, andpoly-dimethyl siloxane/silicon resin hydrophobic surface treatments wereused with Epotal S 440 and other commercially available styrene acrylicresin emulsions from BASF Corporation.

In Table 7 (below), Epotal S 440 was incrementally treated withcommercially available poly-dimethyl siloxane hydrophobizingsubstituents from Momentive Performance Materials. The treatment wasadded to the Epotal S 440 under mild agitation at room temperature. Noevidence of a chemical reaction was observed during the treatmentprocess.

A commercially available uncoated board base paper from MeadWestvaco(MWV) was then coated. The test sheets were allowed to equilibrate in aconstant temperature and humidity environment at 25.5° C. and 40% R.H.and were then subjected to Cobb testing (TAPPI Method T441). The dataclearly demonstrates the benefits of the treatment method.

TABLE 7 Coat Weight 30 minute Cobb Avg Sample ID (g/m²) (g/m²) Raw BaseStock 0.0 80.65 Epotal S 440 control 20.2 5.10 Epotal S 440 with 0.25part of 19.6 7.10 hydrophobizing chemistry Epotal S 440 with 0.50 partof 21.0 9.80 hydrophobizing chemistry Epotal S 440 with 0.75 part of20.2 7.55 hydrophobizing chemistry Epotal S 440 with 1.0 part of 20.33.70 hydrophobizing chemistry Epotal S 440 with 1.25 part of 20.4 3.70hydrophobizing chemistry Epotal S 440 with 1.50 part of 19.1 4.10hydrophobizing chemistry Epotal S 440 with 1.75 part of 19.4 3.00hydrophobizing chemistry Epotal S 440 with 2.0 part of 20.5 3.65hydrophobizing chemistry

Example 4: Comparison of a Coating System Including Pre-Treating PigmentVersus a System Including Untreated Pigment with Post Addition ofHydrophobizing Chemistry

Example 3 demonstrated that a method for hydrophobizing a styreneacrylic resin emulsion can be used to obtain an aqueous based coatingsystem with untreated pigments that includes many of the desiredproperties of the coating system include the surface treated pigment. Anumber of studies were subsequently conducted to further compare the twotypes of coating systems. In the comparisons, silane, siloxane, andpoly-dimethyl siloxane/silicon resin hydrophobic surface treatments ofthe pigments and the post-addition for untreated pigments. Both usedEpotal S 440 and other commercially available styrene acrylic resinemulsions from BASF Corporation, as the polymer emulsion system.

In Tables 8 and 9 below, two coatings were tested. The first coatingincluded pigments pre-treated with siloxane (Dow Corning 2-1912, whichis a commercially available siloxane from Dow Corning) in an amount of1% without any post-addition of hydrophobizing substituents. The secondcoating included untreated pigments with post-addition of the samesiloxane used in the first coating as the hydrophobizing substituent.Both coatings included a combination of Epotal S 440 and Acronal S 504,which is a commercially available acrylic resin emulsion from BASFCorporation. The treatment and pigments were added to the Epotal S 440under mild agitation at room temperature.

Rheological stability of the coatings were tested, the results of whichare presented in Table 10 below. Also, a commercially available uncoatedboard base paper from MeadWestvaco was then coated with each of the twocoatings to form test sheets for Cobb testing. The test sheets weresubjected to TAPPI Method T441 to obtain Cobb Coffee absorptionaverages. The Cobb test results are also presented in Table 10 below.The data demonstrates that many of the benefits of embodiments of thecoating system including surface treated pigments can also be obtainedin embodiments of the coating system with untreated pigments wherepost-addition of hydrophobizing substituents are added.

TABLE 8 First Coating With Pre-Treated Pigment And No Post-AdditionComponents Solids (%) Dry Wet Epotal S 440 47.6 56.25 65.23 Acronal S504 49.4 18.75 20.95 DC 2-1912 100 0.25 0.14 Defoamer 100 0.05 0.03Untreated Kaolin 100 24.75 13.7 Pre-treated Kaolin 100 0 0

TABLE 9 Second Coating With Untreated Pigment and Post-AdditionComponents Solids (%) Dry Wet Epotal S 440 47.6 56.25 55.42 Acronal S504 49.4 18.75 17.80 DC 2-1912 100 0 0 Defoamer 100 0.05 0.02 UntreatedKaolin 100 0 0 Pre-treated Kaolin 100 25 11.7

TABLE 10 First Coating Second Coating Brookfield viscosity (50 rpm)First week 640 600 Second week 600 640 Third week 600 640 High shear(dynes/4400 rpm) First week 28.6 28.4 Second week 28 28.4 Third week27.3 28.4 30 min Cobb Coffee 10.0 10.7 Absorption Avg (g/m²)

The coatings were also visually tested for nibs and fish eyes. The firstcoating had some fish eyes present, no nibs using a spatula rub testafter 30 minutes of mixing, and pigment addition had minimal float. Thesecond coating had no fish eyes, no nibs using a spatula rub test after2 hours of mixing, and pigment addition floated.

Example 5: Coatings Systems Compared for Both Water and Water VaporTransmission Rates

A series of evaluations were conducted to test the water resistantcoating systems to water vapor barrier coatings. In this example, threestyrene acrylic resin emulsions and two kaolin based pigment systemswere evaluated. Binding systems selected were:

-   -   Epotal S 440: A commercially available a soft film forming SA        emulsion engineered for direct contact with food. The product pH        was 8.0, Acid Number of 64, and a Tg (C) of −27° C.    -   Resin Emulsion A: A water based, high performance, hybrid RC        acrylic emulsion polymer offered by BASF Corporation. It is        typically 40% solids, and was used as received. Its Tg (C) was        15° C. and 80° C. with an average particle size obtained from        PCS of 163 nm. This emulsion offered improved resistance        properties and low COF.    -   Copolymer A: An aqueous copolymer dispersion of butyl acrylate        and styrene offered commercially by BASF Corporation. Its target        use is in ceramic tile mastic adhesives, primers and other        construction adhesives. Benefits include good water resistance        and strength.

The coating substrate was a heavyweight kraft liner. The curve of thesheets and the difference in water beading behavior between thedifferent sides of the sheets suggested that it had undergone some typeof surface treatment. Other characteristics are described below in Table11.

TABLE 11 Base Paper Properties Caliper 385 pm Basis weight 260 g/m²Roughness 8.95 pm Permeance - Gurley 66.7 seconds Permeance - Bendtsen178.2 ml/min

Pigments were limited to kaolin that were coarse and platy (described inExamples 1 and 2); that was dried in a flocculated state (3.2 pH); andTranslink 37. Coating systems were made by mixing the pigments into thetarget binding system with a small amount of defoamer (less than 0.20parts) and enough water to bring the coatings to 50% solids by weight.The pigment to binder (P/B) ratio of the coatings was 1:1.

Coating systems were prepared by weighing the binder system and defoamer(Octafoam DFI-51 by Hi Mar Specialty Chemicals) into a small beaker. Thebeaker contents were agitated by a Dispermat mixer fitted with a sawtoothed blade. Mixing speed was ramped up until a vortex was created atthe agitator shaft. The pigment system was added gradually into thevortex, and once the full amount had been added, the mixing speed wasincreased to 1200 rpm and the slurry was allowed to mix for 10 minutes.The total sample size was approximately 100 g. Coating system solidswere targeted at 59.0 percent.

The coatings were applied with wire-wound bars chosen to give the targetdry coating weight. To get 10 g/m² coat weight with coatings at 50%solids, a K3 applicator bar was used. The coated sheets were dried inthe 50° C. oven for 1 minute. For 30 g/m² dry coat weight, the coatingsystems based on Epotal S 440 and Copolymer A were applied in 2 coats;first with the K3 bar, followed by 1 minute in the oven, then anothercoat with the K5 bar. The coating system based on Resin Emulsion A couldnot be overcoated. They were applied in a single pass with the K7 bar.Initial Cobb testing on some of the sheets showed a great dependence ofproperties as a function of drying time, therefore, the 30 g/m² coatedsheets were allowed to dry in oven at 50° C. for approximately 2 hours.

Water resistance of the coatings was tested with the Cobb method,described by TAPPI T 441. A test area of 100 cm² was used, but in thiscase the testing time was 30 minutes instead of 2 minutes. MVTR wasmeasured on the MOCON Permatran-W Water Vapor Permeation MeasurementSystem. This instrument measures the transmission rate of water vaporthrough a substrate by keeping the atmosphere one side of the sample ata constant relative humidity while flooding the other side with a streamof dry nitrogen. The nitrogen flows past the substrate and then on to anIR detector which measures how much water has been picked up by the gas.The permeability of the uncoated base paper was too high to allow MVTRmeasurement by the MOCON Permatran-W Water Vapor Permeation MeasurementSystem. The amount of water vapor that came through overwhelmed theinstrument's detector. The MVTR of this sample was alternativelymeasured by the cup method (ASTM D 1653).

Table 12 denotes the 30 minute Cobb data at both 10 g/m² and 30 g/m²coat weights. Table 13 denotes MVTR values at 30 g/m² coat weight.

TABLE 12 30 minute Cobb data 30-minute 30-minute Cobb @ 10 g/m² Cobb @30 g/m² Coating dry coat weight dry coat weight Epotal S 440 11.6 NAEpotal S 440/Translink 11.5 3.6 37 Epotal S 440/Coarse 55.6 16.6 KaolinCopolymer A 77.1 3.4 Copolymer A/Translink 37.7 3.5 37 CopolymerA/Coarse 96.3 56.4 kaolin Resin Emulsion A 12.9 0.0 Resin Emulsion A/35.6 7.5 Translink 37 Resin Emulsion A/ 47.3 5.4 Coarse kaolin Baresubstrate 104.3

The data showed that increasing coating weight improves the waterresistance of the coated liner. In general, at a pigment to binder ratioof 1:1, the untreated coarse, platy kaolin does not provide the samelevel of water resistance as 100% resin. However, Translink 37 generallyhas a beneficial or comparable effect on water resistance depending onthe resin used with it. Translink 37 and Epotal S 440 at 10 g/m² havewater resistance comparable to 100% Epotal s 440 and 100% Resin EmulsionA. It is significantly better than 100% Copolymer A. The combination ofcoarse platy kaolin and Resin Emulsion A at 30 g/m² has exceptionalperformance. This higher coating weight, however, might proveuneconomical in manufacturing practice. The choice of using afilled/extended system must be weighed against the potential necessityof increasing the coating weight to achieve the desired properties. TheJoncryl 3030/Translink 37 gave results that would make this systemviable for applications that require high level of water resistance.

For MVTR testing, the sheets coated with 30 g/m² dry coat weight weretested at tropical conditions; of 38° C. and 90% relative humidity.

TABLE 13 MVTR Test Results MVTR at tropical conditions and @ 30 g/m²Coating dry coat weight Epotal S 440 409.5 Epotal S 440/Translink 37830.9 Epotal S 440/Coarse kaolin 277.2 Copolymer A 467.8 CopolymerA/Translink 608.9 37 Copolymer A/Coarse 330.1 kaolin Resin Emulsion A227.2 Resin Emulsion A/Translink 37 1204 Resin Emulsion A/Coarse kaolin442.1 Bare substrate 1439.7

In MVTR testing, Translink 37 does not appear to provide beneficialeffects relative to the neat binders. The coarse, platy kaolin pigmentdemonstrates a beneficial effect on vapor transmission resistance whencombined with Epotal S 440 and Copolymer A but not with Resin EmulsionA. It can be concluded that different coating formulations may benecessary to achieve desired liquid water resistance and water vaporbarrier properties. To improve water resistance, a hydrophobicallytreated kaolin seems to work best when combined with the right resinlike Epotal S 440. For vapor transmission resistance, a pigment thatprovides tortuosity, i.e., increases the path travelled by vapor as itpenetrates and passes through the coating appears to be needed. Thecoarse, platy kaolin pigment used in this study appears to provide thetight particle packing needed and when used with the proper resin canenhance MVTR.

Example 6—Dispersing Effect of Silanes, Siloxanes, andPoly-Siloxane/Silicone Resin Blends on Styrene Acrylic Resin Emulsions

While assessing the benefits of hydrophobically surface treated pigmentsystems in water barrier applications, an unexpected finding was thatsilanes, siloxane, and poly-siloxane/silicone resin treatments have abeneficial dispersing effect on styrene acrylic resin emulsions. Theresulting lower coating system viscosity offers multiple benefits—chiefbeing the ability to increase pigment system loading with acceptablefilm forming capabilities. It also provides a needed degree of freedomto include additives that will improve coating efficiency and thequality of the film surface.

Table 14 demonstrated the benefits of this dispersion/coating systemviscosity. Here, the coarse and platy kaolin pigment cited earlier wasdried in the flocculated state (3.2 pH) and was hydrophobized by surfacetreatment with a commercially available siloxane hydrophobizingtreatment (up to 2.0 percent by weight) supplied by MomentivePerformance Materials. For comparison, the same kaolin pigment was leftuntreated and was also hydrolyzed by magnesium stearate surfacetreatment (up to 3.0% by weight). Epotal S 440 was selected as thebinder component of the coating systems.

The coating systems were prepared by weighing the Epotal S 440 anddefoamer (Octafoam DFI-51 from Hi Mar Specialty Chemicals) into a smallbeaker. The beaker contents were mixed with a Dispermat mixer fittedwith a saw toothed blade. Mixing speed was ramped up until a vortex wascreated at the agitator shaft. The pigment system was added graduallyinto the vortex, and once the full amount had been added, the mixingspeed was increased to 1200 rpm and the slurry was allowed to mix for 10minutes. The total sample size was approximately 100 g. Coating systemsolids were targeted at 59.0 percent. Brookfield viscosity was measuredinitially and after 24 hours to factor out the potential for entrainedair biasing results as seen with siloxane treatment.

TABLE 14 1:1 Epotal S 1:1 Epotal S 440/Coarse 1:1 Epotal S 440/Coarsekaolin + Epotal S 440/Coarse kaolin + Magnesium Coating System 440kaolin siloxane Stearate Coating System 46.0% 58.3% 59.0% 59.0% SolidsInitial Brookfield 1200 cps. 2100 cps. 1650 cps. 2300 cps. Viscosity No.3 @ 20 RPM 24 Hour 1250 cps. 2300 cps.  625 cps. 2550 cps. BrookfieldViscosity No. 3 @ 20 RPM

The dispersion benefits seen with the siloxane surface treatment applyto a range of reactive silicone fluids. Silane substituent (i.e.,vinyl-tris(2-methoxyethoxy)silane), siloxanes andpoly-dimethylsiloxane/silicone resin blends were tested. To onepracticed in the art, it should be readily apparent that this findingcan be extended to carbon based analog chemistries as well as othercompounds exhibiting similar performance characteristics. Thisdispersion benefit was seen in the range of styrene acrylic resinemulsions thus far tested in water barrier applications.

Example 7: Efficient Incorporation of Hydrophobic Pigment Systems inStyrene Butadiene Latex

During the development of novel water barrier coating systems, theindustry suggested a need for a styrene butadiene latex based coatingsystem. As stated in the aforementioned examples, a highly efficientwater barrier coating system contains a hydrophobized pigment system ora hydrophobized styrene acrylic resin emulsion. To those skilled in theart, a hydrophobized pigment cannot be readily dispersed into a waterbased styrene butadiene latex. To facilitate this need in themarketplace, a novel method of pigment system incorporation has beendeveloped which capitalizes on the enhanced dispersing effect ofreactive silicone fluids such as silanes, siloxane, andpoly-siloxane/silicone resin blends on styrene acrylic resin emulsions(Example 6). The hydrophobized pigment system was first added to astyrene acrylic resin emulsion. This system was then readily dispersedinto styrene butadiene latex.

The data in Table 15 demonstrates the performance of Translink 37 and anew hydrophobized water barrier pigment system that have beenincorporated into a commercially available styrene butadiene latex(Epotal 4430). The new pigment system comprises thermally treated kaolinthat has been hydrophobized by surface treatment with apoly-dimethylsiloxane/high molecular weight silicone resin blend(available from Dow Corning). The designation of this new product isProduct 100. Product 100 exhibits improved water barrier properties(Cobb) when compared to Translink 37 in coating systems tested.

Product 100 is also considered to be acceptable for food packaging,since the poly-dimethylsiloxane/high molecular weight silicone resinblend is compliant with food safety, as each of the individualsubstituents is approved by the FDA for applications in food.

Translink 37 and Product 100 were incorporated into Epotal 4430 using aslittle as 9.0 dry parts of styrene acrylic resin emulsion (Epotal S 440in this example) to 100 parts of the pigment system. In particularembodiments, chemical order of addition can be critical. Mixing can beaccomplished with a Dispermat mixer equipped with a saw tooth disk.First, approximately 80% of the required Epotal S 440 was added to themakeup water required for the coating system. The required Product 100or Translink 37 pigment system was then added to this blend. Thesehydrophobized pigment systems floated but will readily incorporate whenthe remaining Epotal S 440 is added with agitation set at 2000 RPM.Complete incorporation was achieved without the need for othersurfactants/defoamers within 5 minutes. The resulting slurry is stable.There is no preferential order of addition needed when adding the EpotalS 440/pigment system slurry and target styrene butadiene latex (Epotal4430 in this case). Only moderate agitation (1200 RPM) is required forefficient mixing. 0.1 parts defoamer (Octafoam DFI-51 from Hi MarSpecialty Chemicals) was added during this final mixing step to minimizethe presence of entrained air in the costing system. A thickening aid(Sterocoll FD) was added to raise the coating system Brookfieldviscosity above 500 cps.

TABLE 15 Pigment Coating System Brookfield Viscosity Hercules ViscositySystem Solids (%) (2@100 RPM) @16 Dynes Translink 37 57.0 80 960 RPMProduct 100 56.7 90 567 RPM

Improved Sealability and Blocking of Coated Substrates

In certain embodiments, coatings that provide a barrier to water,moisture, grease, oil, oxygen etc. should also have the ability to forma seal and not block during the manufacturing process. For example,paper or paperboard used in a cup that will contain cold or hot liquidsmust be able to be sealed when the front and back sides of the paper orpaperboard are joined and subjected to elevated temperature and pressureand the seal itself must also be resistant to liquid or moisture vaporand maintain its integrity in their presence. To further improve on theheat sealability of the coating systems of this invention, resincombinations were tested. Two pigments were evaluated in these studies:Product 101, a thermally treated kaolin pigment, and Product 100, athermally treated kaolin pigment that has been hydrophobized by acommercially available poly-dimethylsiloxane/high molecular weightsilicone resin blend.

The binder systems tested were composed of the following components:

-   -   Epotal S 440: A commercially available a soft film forming SA        emulsion from BASF Corporation. It is engineered for direct        contact with food. The product pH was 8.0, Acid Number of 64,        and a Tg(C) of −27° C.    -   Binder A: A commercially available styrene acrylic emulsion from        BASF Corporation. The product pH was 7.6 with an Acid Number of        57, and a Tg(C) of −4° C.    -   Epotal 4430: A commercially available aqueous dispersion of a        carboxylated styrene/butadiene copolymer from BASF Corporation.        Its target use is in the manufacture of laminating adhesives. It        has outstanding mechanical, chemical stability and displays        excellent adhesion.    -   Binder B: A commercially available aqueous dispersion of a        carboxylated styrene/butadiene copolymer from BASF Corporation.

These binder systems were selected and tested based on anticipatedimprovements in heat sealing due to T_(g) or similarity to materialscurrently used in heat sealing processes.

Coatings were applied to the cup stock with wire wound bars on theK-Control Coater. The target dry coat weight was 5.7 g/m². In manycases, this was achieved with 2 layers of a coating at 40% solids withthe K2 bar; in other cases, depending on the percent solids andviscosity or the presence of wax, other combinations of bars or a singlelayer coating was used. Coated sheets were dried 2 minutes at 50° C.after each layer, then allowed to equilibrate in the constanttemperature and humidity room for 2 days before testing.

Cobb testing was performed according to TAPPI test method T-441. Thetest area was 25 cm² and the test time was 30 minutes. Four replicatesof each condition were tested. Based on previous lab and trial work itwas established that for hot cups a Cobb value of 12 g/m² was acceptableso any sample with performance equal or better than that material wasconsidered acceptable in our testing.

Heat sealing was evaluated on a Sencorp model 12ASL/1 sealer. Thetemperature of both the top and bottom jaws was set at 600° F. for alltest conditions. Coated sheets were placed face to face and sealed atvarious times and pressures. The most common sealing times were 0.25,0.35 and 0.5 seconds, based on information that cup sealing rates of 150cups/minute (0.4 seconds/cup) were acceptable. Pressures were variedfrom 20 to 30 to 40 psi. After sealing and cooling to room temperature,the two pieces of board were pulled apart, and rated on the level ofadhesion. Samples were given a rating of 1 to 5, based on the followingscale:

1—No adhesion2—Adhesion, but no picking or fiber tears3—Adhesion with coating transfer or slight fiber tear (<5% or surfacearea)4—Some fiber tear (5-50%)5—Fiber tear (>50%)

Since maximum adhesion at the lowest possible times and pressures wasdesirable, higher ratings are better.

Blocking resistance was evaluated with a Koehler Instruments blocktester. The samples were cut into 1.5″×1.5″ pieces and placedface-to-face and face-to-back. A small metal plate with a circular holewas placed on top of the samples to keep them positioned, a spring witha circular metal face is then placed on top. The spring was compressed,in this case to 20 mm, corresponding to a pressure of 15.2 psi, the testrig was then placed in a 50° C. oven for 16 hours. At the end of thattime, the rig was removed from the oven, and the samples were removedand allowed to cool to room temperature. Once cooled, the individualpieces were separated and the degree of adhesion noted. Samples weregiven a rating of 1 to 5, based on the following scale:

1—No adhesion2—Slight adhesion3—Some adhesion, no material transfer between surfaces4—Strong adhesion, perhaps with material transfer between surfaces5—Fiber tear

In this case, because blocking in a coated roll should be minimized,lower ratings are better.

Example 8—Evaluation of Binder Combinations

In this group of tests, the effects of different binders were evaluated.Binder A was used as a control because it is used in other heat sealapplications, but not approved for direct food contact. In Table 16,Cobb and blocking test results are delineated for the bindercombinations evaluated. The heat sealing results are reported in Table17.

TABLE 16 Face-to-face Dry coat Cobb blocking (lower Description weight(g/m²) (g/m²) better) PE - extruded commercial N/A 0.61 2 Standardpigmented coating N/A 12.04 3 Epotal S 440 5.7 6.45 2 Binder A 5.7 6.805 Epotal S 440 + Epotal 4430 5.7 5.26 3 (75:25) Epotal S440 + Binder B5.7 4.85 3 (75:25)

TABLE 17 Time (sec) PE at 20 PSI PE at 30 PSI PE at 40 PSI 0.5 4-5 4-54-5 0.35 4-5 4-5 4-5 0.25 4 4-5 4-5 Standard Standard Pigmented CoatingStandard Pigmented Pigmented Time (sec) at 20 PSI Coating at 30 PSICoating at 40 PSI 0.5 1 4 4 0.35 1-2 2 — 0.25 1 1-2 — Epotal Epotal S440 at 20 Epotal S 440 at 30 S 440 at 40 Time (sec) PSI PSI PSI 0.5 — —— 0.35 3 — 5 0.25 3 3 4 Binder Time (sec) Binder A at 20 PSI Binder A at30 PSI A at 40 PSI 0.5 4-5 4-5 4-5 0.35 5 4-5 4-5 0.25 4 4-5 4-5 EpotalS 440 + Epotal S 440 + Epotal S 440 + Epotal 4430 at 20 Epotal 4430 at30 Epotal 4430 at 40 Time (sec) PSI PSI PSI 0.5 4-5 4-5 4-5 0.35 4-5 4-54-5 0.25 5 4-5 4-5 Epotal Epotal Epotal S 440 + Binder S 440 + Binder S440 + Binder Time (sec) B at 20 PSI B at 30 PSI B at 40 PSI 0.5 4-5 4-54-5 0.35 4-5 4-5 4-5 0.25 4 4-5 4-5

All of the coatings have acceptable Cobb values and all, but Binder A,have reasonably acceptable blocking. Epotal S 440 by itself as well asthe other binders sealed better than the pigmented standard coating. Theperformance of the others showed that there is room to improve sealingperformance by changing the binder system.

It might be expected that the addition of pigment will reduce theability of the coating to seal, but may improve Cobb performance andreduce blocking. Two kaolin pigments were tested: Product 101 andProduct 100. Each was dispersed with a Cowles blade in Epotal S 440 at aratio of 55 parts kaolin to 45 parts resin solids, along with defoamer.Table 18 lists the systems tested and Table 19 the heat sealing results.

TABLE 18 Face-to-face Dry coat blocking (lower Description weight (g/m²)Cobb (g/m²) better) 100% Epotal S 440 5.7 6.45 2 Pigmented coating N/A12.04 3 (Epotal S 440 + kaolin) 45% Epotal S 440 + 5.7 5.35 1.5 55%Product 100 45% Epotal S 440 + 5.7 13.59 1.5 55% Product 101

The combination of Epotal S 440 and Product 100 (hydrophobically surfacetreated calcined kaolin) gave superior Cobb values to the untreatedcalcined kaolin. However, all of the exemplary systems gave acceptableCobb results for cold and hot cup applications. The pigmented systemsgave superior blocking results.

TABLE 19 Time (sec) Epotal S 440 at 20 PSI Epotal S 440 at 30 PSI EpotalS 440 at 40 PSI 0.5 — — 4-5 0.35 3 — 5 0.25 3 3 4 Pigmented Standard atPigmented Standard at Pigmented Standard at Time (sec) 20 PSI 30 PSI 40PSI 0.5 1 4 4 0.35 1-2 2 — 0.25 1 1-2 1-2 Epotal S 440 + Product EpotalS 440 + Product Epotal S 440 + Product Time (sec) 101 at 20 PSI 101 at30 PSI 101 at 40 PSI 0.5 1 2 3 0.35 1-2 1-2 1-2 0.25 1-2 1-2 1-2 EpotalS 440 + Product Epotal S 440 + Product Epotal S 440 + Product Time (sec)100 at 20 PSI 100 at 30 PSI 100 at 40 PSI 0.5 2 3 4 0.35 1 2 2 0.25 1-21-2 1-2

The heat seal results indicate that the addition of kaolin pigment in a55:45 ratio negatively impacts heat sealability overall, resulting inless adhesion at each sealing condition when compared with Epotal S 440by itself, but yields results comparable to the Pigmented Standard.

Blends of Epotal S 440 and Epotal 4430 were next tested (Table 20 andTable 21) to evaluate the effect of the binder system on heatsealability. A 75:25 blend of Epotal S 440 and Epotal 4430 (referred toas “Binder 1”) and a blend of 43:57 75:25 blend of Epotal S 440 andEpotal 4430 (“Binder 2”). The kaolin pigment system was dispersed ineach coating system at a pigment to binder ratio of 55:45.

TABLE 20 Dry coat Blocking Description weight (g/m²) Cobb (g/m²) (lowerbetter) Epotal S 440 + 5.7 5.35 1.5 Product 100 Binder 1 + Product 1005.7 3.80 2 Binder 2 + Product 100 5.7 3.97 3

TABLE 21 Epotal S 440 + Product Epotal S 440 + Product Epotal S 440 +Product Time (sec) 100 at 20 PSI 100 at 30 PSI 100 at 40 PSI 0.5 2 3 40.35 1 2 2 0.25 Binder 1 + Product 100 Binder 1 + Product 100 Binder 1 +Product Time (sec) at 20 PSI at 30 PSI 100 at 40 PSI 0.5 3 5 0.35 3 3 40.25 1 1 2 Binder 2 + Product 100 Binder 2 + Product 100 Binder 2 +Product Time (sec) at 20 PSI at 30 PSI 100 at 40 PSI 0.5 2 5 0.35 2 3 30.25

A blend of 75:25 parts Epotal S 440 and Epotal 4430 performs slightlybetter than the blend with more Epotal 4430.

The best formulation tested is comprised of 75:% Epotal S 440/25% Epotal4430 binder system at a pigment to binder ratio 55:45 with Product 100hydrophobically treated kaolin. This represents an improvement over theperformance of the straight Epotal S 440/kaolin system.

Example 9—Evaluation of Blocking Additives

In this group of tests, the effects of different blocking additives wereevaluated. \ In Table 22, blocking test results are delineated for thedifferent additives evaluated. Also, a blocking test results are shownfor coating systems without any blocking additive, but with differentpigment to resin ratios.

The blocking rating is from 0 to 4 with 0 having no delamination, 1-2having noise, and 4-5 having delamination. Cobb coffee is determined inthe same manner as in the previous examples.

Joncryl Wax is a commercially available polyethylene-paraffin waxemulsion from BASF. Joncryl 3025, 3040, and 3050 are commerciallyavailable styrene-acrylic emulsions from BASF. Calson 50 and 65 arecommercially available calcium stearates from BASF. Acronal Optive 4655Xis a commercially available acrylic resin from BASF. Styronal 4606 is acommercially available styrene-butadiene latex binder from BASF.

TABLE 22 MKT2012-0069 Barrier Coating Blocking Improvement Study LabResults Coat weight Static Cobb Samples Description g/m2 Kinetic COFCoffee J110512-01 Control 1 (23.5 M09- 24.7 1.06 0.65 14.9 2033:76.5D2/CR2/SL3) J110512-02 Control 2 (25 M09- 24.4 0.92 0.63 9.9 2033:75Resin G) J110512-03 Joncryl Wax (5.0 parts) 24.4 0.80 0.54 9.5 120J110512-04 Joncryl Wax (10 parts) 24.4 0.86 0.50 7.6 120 J110512-05Joncryl 3025 (23.15 parts) 24.6 0.62 0.54 9.5 J110512-06 Joncryl 3025(46.3 parts) 24.8 0.67 0.55 36.9 J110512-07 Joncryl 3040 (46.3 parts)24.4 0.66 0.52 9.4 J110512-08 Joncryl 3050 (46.3 parts) 24.3 0.53 0.466.9 J110512-09 Calsan 50 (0.5 part) 25.9 1.10 0.73 13.7 J110512-10Calsan 50 (1.0 part) 25.1 1.13 0.74 14.3 J110512-11 Calsan 50 (2.0parts) 24.8 1.07 0.71 15.4 J110512-12 Calsan 65 (0.5 part) 24.7 1.250.75 20.2 J110512-13 Calsan 65 (1.0 part) 24.2 1.18 0.72 15.4 J110512-14Calsan 65 (2.0 parts) 25.2 0.82 0.71 14.7 J110512-15 Acronal Optive(30.2 parts) 24.9 1.07 0.65 10.8 4655X J110512-16 Styronal 4606 (30.2parts) 24.6 0.93 0.69 9.2 J110512-17 D2/CR2/SL3 100% resin 24.3 1.250.78 11.5 (23.5 M09-2033) J110512-18 D2/CR2/SL3 100% resin 25.3 1.160.77 9.7 (23.5 M09-2033) PE Coated PE Coated MWV 16.3 0.36 0.30 1.0Control Control Coated 15 pt MWV 15 pt base MWV (Basis 0.40 0.31 89.6Base supplied wt) 278.9 MKT2012-0069 Barrier Coating BlockingImprovement Study Lab Results Samples Description Blocking HS HS+ CobbJ110512-01 Control 1 (23.5 M09- 4 4 4 12.81 2033:76.5 D2/CR2/SL3)J110512-02 Control 2 (25 M09- 3 3 3.5 10.4 2033:75 Resin G) J110512-03Joncryl Wax (5.0 parts) 1 1 1.5 9.45 120 J110512-04 Joncryl Wax (10parts) 1 1 1.5 8.12 120 J110512-05 Joncryl 3025 (23.15 parts) 1 1 144.91 J110512-06 Joncryl 3025 (46.3 parts) 0 0 0.5 1.66 J110512-07Joncryl 3040 (46.3 parts) 1 1 1.5 5.86 J110512-08 Joncryl 3050 (46.3parts) 0 0 0.5 7.42 J110512-09 Calsan 50 (0.5 part) 3 3 3.5 10.96J110512-10 Calsan 50 (1.0 part) 2 2 3 11.28 J110512-11 Calsan 50 (2.0parts) 3 3 3.5 9.49 J110512-12 Calsan 65 (0.5 part) 3 3 3.5 12.73J110512-13 Calsan 65 (1.0 part) 3 3 3.5 13.96 J110512-14 Calsan 65 (2.0parts) 3 3 3.5 10.92 J110512-15 Acronal Optive (30.2 parts) 1 1 1.5 8.544655X J110512-16 Styronal 4606 (30.2 parts) 2 2 3 8.29 J110512-17D2/CR2/SL3 100% resin 3 3 3.5 8.74 (23.5 M09-2033) J110512-18 D2/CR2/SL3100% resin 3 3 3.5 9.77 (23.5 M09-2033)

While the invention has been disclosed with reference to specificembodiments, it is apparent that other embodiments and variations ofthis invention may be devised by others skilled in the art withoutdeparting from the true spirit and scope of the invention. The appendedclaims are intended to be construed to include all such embodiments andequivalent variations.

What is claimed is:
 1. A method for preparing an aqueous based coatingsystem for coating onto paper and/or paperboard for providing barrier toliquid, moisture vapor, oil and grease, comprising: surface treating apigment to form a pigment system; and mixing a polymer emulsion systemor natural based binding system with the pigment system.
 2. The methodof claim 1 wherein a component of the pigment system has been modifiedby a thermal treatment process.
 3. The method of claim 1, wherein thepigment is surface treated with materials selected from the groupconsisting of surfactants, hydrophobically-modified polymers,styrene-acrylic resin emulsion, styrene-butadiene latex emulsions,blends of styrene acrylic and styrene butadiene latex emulsions, andsilanes, siloxanes, siloxane/silicone resin blends, and theircarbon-based analogs.
 4. The method of claim 1, wherein the pigment isat least one inorganic material selected from kaolin, bentonite, mica,talc, attapulgite, and zeolite.
 5. The method of claim 1, wherein thepolymer emulsion system comprises a styrene-acrylic resin emulsion. 6.The method of claim 1 further comprising mixing an additive to improveblocking with the polymer emulsion system or natural based bindingsystem and pigment system.
 7. The method of claim 6, wherein theadditive to improve blocking comprises a material selected from thegroup consisting of calcium stearate, styrene-acrylic resin, acrylicresin, and polyethylene-paraffin wax emulsion.
 8. An aqueous basedcoating system for coating onto paper and/or paperboard for providingbarrier to liquid, moisture vapor, oil and grease, comprising a polymeremulsion system or natural-based binding system and a pigment system,wherein the pigment system comprises a surface treated pigment.
 9. Theaqueous based coating system of claim 8, wherein a component of thepigment system has been modified by a thermal treatment process.
 10. Theaqueous based coating system of claim 8, wherein the pigment has beensurface treated with materials selected from the group consisting ofsurfactants, hydrophobically-modified polymers, styrene-acrylic resinemulsion, styrene-butadiene latex emulsions, blends of styrene acrylicand styrene butadiene latex emulsions, and silanes, siloxanes,siloxane/silicone resin blends, and their carbon-based analogs.
 11. Theaqueous based coating system of claim 8, wherein the pigment comprisesat least one inorganic material selected from kaolin, bentonite, mica,talc, attapulgite, and zeolite.
 12. The aqueous based coating system ofclaim 8, wherein the polymer emulsion system comprises a styrene-acrylicresin emulsion.
 13. The aqueous based coating system of claim 8 furthercomprising an additive to improve blocking.
 14. The aqueous basedcoating system of claim 13, wherein the additive to improve blockingcomprises a material selected from the group consisting of calciumstearate, styrene-acrylic resin, acrylic resin, andpolyethylene-paraffin wax emulsion.
 15. A coating system for coatingonto a paper and/or paperboard comprising a pigment and a polymeremulsion or natural-based binding system that has been hydrophobized bythe addition of materials selected from the group consisting of silanes,siloxanes, siloxane/silicone resin blends, and their carbon-basedanalogs.
 16. The coating system of claim 15, wherein the pigment hasbeen modified by a thermal treatment process.
 17. The aqueous basedcoating system of claim 15, wherein the pigment comprises at least oneinorganic material selected from kaolin, bentonite, mica, talc,attapulgite, and zeolite.
 18. The coating system of claim 15, whereinthe pigment has been surface treated to form a pigment system.
 19. Thecoating system of claim 18, wherein the pigment system comprises surfacetreated kaolin having a particle size of at least 20% by weight finerthan 2 micrometers.
 20. The coating system of claim 18, wherein thepigment has been surface treated with the group selected fromsurfactants, hydrophobically modified polymers, styrene-acrylic resinemulsion, styrene-butadiene latex emulsions, blends of styrene acrylicand styrene butadiene latex emulsions, and silanes, siloxanes,siloxane/silicone resin blends, and their carbon-based analogs.
 21. Thecoating system of claim 15, wherein the polymer emulsion systemcomprises a styrene-acrylic resin emulsion.
 22. The coating system ofclaim 15 further comprising an additive to improve blocking.
 23. Thecoating system of claim 22, wherein the additive to improve blockingcomprises a material selected from the group consisting of calciumstearate, styrene-acrylic resin, acrylic resin, andpolyethylene-paraffin wax emulsion.
 24. A method for preparing anaqueous based coating system for coating onto paper and/or paperboardfor providing a barrier to liquid, moisture vapor, oil and grease,comprising: mixing a polymer emulsion system or natural based bindingsystem with a pigment; and hydrophobizing the polymer emulsion system ornatural based binding system by adding a material selected from thegroup consisting of silanes, siloxanes, siloxane/silicone resin blends,and their carbon-based analogs.
 25. The method of claim 24, wherein acomponent of the pigment system has been modified by a thermal treatmentprocess.
 26. The method of claim 24, wherein the pigment is surfacetreated with materials selected from the group consisting ofsurfactants, hydrophobically-modified polymers, styrene-acrylic resinemulsion, styrene-butadiene latex emulsions, blends of styrene acrylicand styrene butadiene latex emulsions, and silanes, siloxanes,siloxane/silicone resin blends, and their carbon-based analogs.
 27. Themethod of claim 24, wherein the pigment is at least one inorganicmaterial selected from kaolin, bentonite, mica, talc, attapulgite, andzeolite.
 28. The method of claim 24, wherein the polymer emulsion systemcomprises a styrene-acrylic resin emulsion.
 29. The method of claim 24further comprising mixing an additive to improve blocking with thepolymer emulsion system or natural based binding system and pigment. 30.The method of claim 29, wherein the additive to improve blockingcomprises a material selected from the group consisting of calciumstearate, styrene-acrylic resin, acrylic resin, andpolyethylene-paraffin wax emulsion.